Got Seaweed?
Birch Aquarium at Scripps
This activity outline was developed for use in a variety of informal venues. By design, it
provides the content, pedagogy and strategy necessary for implementation by both the
novice and experienced informal educator. It is expected that this outline will be adapted
and improved upon by the user. We welcome your feedback!
Theme and Synopsis of the Activity
Explore seaweed samples and discover that seaweed plays a more important role in your
life than you may think. Learners use different criteria to sort the seaweeds, and then are
guided to sort the seaweed based on color. Visitors also may observe what happens when
powdered seaweed is mixed with water, and predict why we might add such seaweed
products to food found in our cupboards. They then find out which foods do contain
seaweed by checking the ingredients lists of some common foods.
Audience and Setting Learners of all ages in groups up to 6 people. It may be possible
for a facilitator to work with several of these groups if their start is staggered. Possible
settings include anywhere outside or inside the informal science center, in the public
exhibit space or in a classroom.
Activity Goals Learners will:
• Understand seaweed are diverse plant-like organisms, with many shapes, colors
and sizes
• Observe how seaweed acts as a binding/thickening agent in food, by mixing
alginate with water
• Recognize and/or identify seaweed-based ingredients when reading product
ingredient lists
Concepts
• Scientists sort seaweeds by color, into red, green and brown types.
• Seaweeds are edible plant-like organisms that grow in the ocean. People consume
them as sea vegetables and in processed food products.
• Dried seaweed is able to absorb and hold on to water. We add dried seaweed to
food products that we want to remain moist or maintain a slimy texture, to
stabilize food, to thicken food and to add color.
Ocean Literacy Principles
5. The ocean supports a great diversity of life and ecosystems.
c. Some major groups are found exclusively in the ocean. The diversity of major groups
of organisms is much greater in the ocean than on land.
d. Ocean biology provides many unique examples of life cycles, adaptations and
important relationships among organisms (Symbiosis, predator-prey dynamics and
energy transfer) that do not occur on land.
6. The ocean and humans are inextricably interconnected.
© 2009 Birch Aquarium at Scripps
Communicating Ocean Sciences to Informal Audiences
b. From the ocean we get foods, medicines, and mineral and energy resources. In
addition, it provides jobs, supports our nation’s economy, serves as a highway for
transportation of goods and people, and plays a role in national security.
Materials
6’ Table
Chair (optional)
Table cover
1-2 stools
Exploration 1—Seaweed, the real stuff:
Small samples of brown, red and green seaweed
Plastic animal tub, small or large, ¼ full of seawater
Dried seaweed, natural and/or packaged (optional)
Exploration 2—Seaweed slime:
Alginate (powdered brown seaweed)
1oz. Plastic cups with lids (enough for one set per participant) or 3 oz. paper cups
Beaker or jar of fresh water
Wooden stir sticks, 3-4 depending on number of participants
Damp cloth
Exploration 3—Seaweed in everything:
5-6 Product containers/boxes with seaweed in ingredients (see Prep Section)
3-4 Magnifying lens
Laminated list of seaweed “code names” found in ingredients lists:
Carrageenan, Algin/Alginate, Agar (see Prep Section)
Prep Section
Collect seaweed samples
Purchase Alginate powder
Write out the “code names” Carrageenan, Algin/Alginate, and Agar, and laminate the list
Collect containers that list seaweed and any of the following words as ingredients:
Carrageenan, Alginate, Sodium Alginate, Calcium Alginate, Alginic acid, and
Agar).
Suggested items to include:
Fruit by the Foot
SaraLee Brand Original Cream Cheesecake
Dreyer's Grand Vanilla Ice Cream
Jell-O Brand Flan
Nestle Quik Chocolate Milk (and other ready-made refrigerated chocolate milks)
Lite Ranch dressing (and other brands of Lite, low oil, no oil salad
dressings)
Fruit and Cereal Bars, such as Lucky Brand Fruit and Grain Cereal Bars
Dole Fruit and Cream Bars
Carnation evaporated milk
Soy milk
Agar or Agar pudding
Hostess Cup Cakes and Fruit Pies
©2009 Birch Aquarium at Scripps
Communicating Ocean Sciences to Informal Audiences
Horchata mix (some)
Seaweed Ramen soup
Seaweed crackers
Hidden Valley Party Dip (dry)
Velveeta cheese
Similac baby formula
Yogurt (some brands)
Eggnog (some brands)
Sunny Delight fruit juice (not California style)
Tofutti
Lucerne non-fat cottage cheese
Hain's pudding mixes
Pie and bakery fillings and glaze on doughnuts
Danish Pastries (store-bought)
Slim Fast (canned drink)
Sushi (ie., California rolls)
Aqua-Fresh, Tom's and Ultra Brite toothpastes
Lucerne clam dip
Kraft Shells and Cheese
Entenmann's Cakes
Seaweed Candy
Nestle's Crunch Ice Cream Bars or Nuggets
Nestle's Quik Powder
Procedure and Set-up
Set up the table with three Exploration Stations.
Exploration #1—Seaweed, the real stuff. Place this station in the center. Keep the
packaged seaweed in the package to prevent it getting wet or misplaced. Have a dry towel
for wiping wet hands.
Exploration #2—Seaweed slime. Give a bit of extra room for the slime activity. This
exploration can wrap around the corner of the table. Plan to have about 4-5 mini-stations
for making slime. Lay out 4-5 cups with a stir stick and paper towel. Have a bowl with
the 1 inch pieces of dried seaweed pieces and the container of Alginate clearly labeled
with a measuring spoon and a pitcher of water closer to the presenter to control amounts
used and to help younger learners.
Exploration #3—Seaweed in everything. Stack the product container boxes so they are
easily seen and accessed by participants. Post the laminated sign and directions and lay
out all the food containers with the hand lenses. This station can wrap around the corner
as well. If you have two presenters, you can have one focus on the slime exploration and
the other on the ingredient and algae explorations. If you have one presenter, the
ingredient exploration can be primarily self-guided. Use signage to help direct your
participants in their task.
©2009 Birch Aquarium at Scripps
Communicating Ocean Sciences to Informal Audiences
Guiding Questions
Have you ever eaten seaweed before?
What did it taste like?
Have you ever seen or touched seaweed?
Where were you when you did this?
Do you remember what it looked like? Felt like?
What does this wet seaweed feel like?
What does this dried seaweed feel like?
What colors is seaweed?
How would you describe the texture of this seaweed?
What do you think would happen if we added this dried seaweed to some water?
How do you think some of these food products are connected to the ocean?
Activity Description
Introduction: Invite visitors to come and participate. Use different methods to pique
their curiosity. For instance, ask them if they have eaten or used any seaweed today, or if
they would like to make slime. Also, let them know that a lot of food manufacturers put
seaweed into all kinds of food that we eat, and then ask them to “come over and we’ll
find out together why they do that.” Once they are hooked, engage the guest in an
exploration. Often the participant will be drawn to one part of the table or the other, let
them guide you to a starting point. If they do not ‘choose’ a place to start, do it for them.
There is no order in which the explorations need to be done, and visitors do not
need to do all three explorations. But the presenter does need to help visitors
make the connections between the explorations if visitors do more than one
exploration and are not making the connections on their own.
Seaweed, the real stuff: Initiate a conversation with the visitors where you talk with
them by asking each other questions and offering to each other descriptions and
explanations. In this exploration, visitors have the opportunity to examine (touch, smell,
think about) many different kinds of seaweed. Two related tasks could help focus their
close examination: compare and categorize the different species of seaweed. The
following are some guiding questions you may want to ask, or tasks you may do with the
visitors. Be sure to encourage visitors to ask their own questions.
• Give visitors free time to look at and feel the seaweed samples.
• Have you have seen, touched, or eaten seaweed before? Where did this
happen/occur? What did they think about the experience? How are these samples
same or different from the seaweed you have seen or eaten?
• Describe to each other what the seaweeds feel like. Which ones feel similar?
• How many different seaweed colors do you see?
• Feel free to ask me any questions about the seaweeds.
• Let’s sort these seaweeds into different groups. Use whatever features/criteria you
want. You might want to group them according to what they have in common.
• Share with everyone the features/criteria you use to sort. (If there are multiple
groups of visitors doing the exploration at the same time, point out how their
criteria are similar and different.)
©2009 Birch Aquarium at Scripps
Communicating Ocean Sciences to Informal Audiences
•
•
If visitors have not done the other explorations, encourage them to check out the
other explorations. Ask them which seaweeds they have eaten before or which
seaweeds do they think that they eat. Tell them that green seaweeds are often
called sea vegetables and recognizable when we eat them, but we may eat
seaweeds all the time and not know. They could discover some foods that
seaweeds are in that they didn’t know about and perhaps be able to predict why
we put seaweed in so many foods in the other two explorations.
If visitors have done the other explorations, then try to make connections between
ideas with visitors from the other seaweed explorations. Ask them how the
sliminess of seaweeds would be helpful in food products.
Potential key ideas to address in this conversation
1. Seaweed comes in many varieties and is only found in certain parts of the ocean.
2. Seaweed needs to be in shallow cold water, rich in nutrients.
3. Seaweed, like the ones in the container, are classified or organized by color and other
characteristics.
4. Some of the most common seaweed in restaurants or stores are red and brown
seaweed.
Seaweed slime: Engage in a conversation with visitors about the slime property of
seaweed. In this exploration, visitors have the opportunity to conduct an experiment to
make seaweed slime in order to figure out why powdered seaweed is a common
ingredient in many food products. They will use powdered seaweed (alginate) and water
for this experiment. Below are some steps for the experiment; followed by some guiding
questions you may want to ask, or tasks you may do with the visitors. Be sure to
encourage visitors to ask their own questions.
1. Give each participant a small cup with a small amount of water in it
(approximately one tablespoon of water in cup).
2. Add a small amount of alginate with the wooden stir stick for each participant,
approximately ¼ teaspoon of powder.
3. Have participants stir the alginate into the water.
•
•
•
Did you know that there is seaweed in many products we use and eat? These
products include toothpaste, ice cream, pudding, and even chocolate milk. Any
ideas why seaweed is necessary in these products? Let’s see if we can figure this
out together.
If visitors have done the “Seaweed, the real stuff” Exploration, then these
questions might be a nice way to connect the two explorations.
o What do you remember about how the real seaweed feels like?
o What about when you rewetted the dried seaweed? What do you
remember about how it felt?
o So do you think this characteristic of seaweed would go away if the
seaweed was dried and then ground up into a fine powder? Well let’s
find out.
After visitors have stirred the powder, invite them to take a closer examination of
the mixture and compare it with others.
©2009 Birch Aquarium at Scripps
Communicating Ocean Sciences to Informal Audiences
o What do you see? Does everyone’s mix look the same? Feel the
mixture. What does it feel like?
o A very little amount of powder was added to the cups. What do you
notice? Describe to each other how this mixture moves and feels.
o Where did all the water go?
o Talk with each other and see if you can figure out how this mixture is
helpful for products like ice cream, toothpaste, and pudding? Keep in
mind what it feels like and what happened to the water.
o What is a question you may want to ask to find out more about this
seaweed powder?
Potential Key ideas to address in this conversation
1. Alginate is a powdered extract of brown seaweed.
2. Alginate is used in many food and other products we use as an emulsifier (e.g., to
keep ingredients mayonnaise, salad dressing, and chocolate milk in suspension);
thickener (e.g., to thicken pie filling so it does not soften the pastry crust); and
stabilizer (e.g., for ice cream, to keep it from forming large ice crystals).
3. These properties are also useful in other products like toothpaste, and in the textile
industry to thicken pastes containing dye.
4. In this experiment, the seaweed powder absorbs the water and “holds onto it” in a
slime. That slime is what emulsifies, thickens, and stabilizes the ingredients in the
products we use.
Seaweed everywhere: Talk with visitors about the presence of seaweed in many
products we use everyday, where we may not even know it. In this exploration, visitors
explore the different products we use everyday that have seaweed in them. They will look
in ingredient lists to find seaweed “codenames” since it is the powdered seaweed extract
that is named in these products, not the actual seaweed itself. The following are some
guiding questions you may find useful want to ask, or tasks you may do with the visitors.
Be sure to encourage visitors to ask their own questions.
• What’s the connection between some of these foods (hold up some of the food
packages) and the ocean?
• Let’s take a look at the ingredients list to find the common ingredients.
• Why do you think seaweed is in so many of these products? Encourage visitors to
share their answers.
o If visitors have not done the other explorations, then this question is a
good way segue them. Tell visitors that they should explore some of the
properties of seaweed in the explorations to try to figure out the answer to
your question.
o If visitors have done the other explorations, then remind visitors about
what they did and noticed about seaweed in those explorations that would
be useful to help them answer your question.
Potential key ideas to address in this conversation
1. Powdered seaweeds are known as agar, carrageenan, and alginate (or algin).
2. These powders come from different species of seaweed.
©2009 Birch Aquarium at Scripps
Communicating Ocean Sciences to Informal Audiences
3. Depending on the seaweed species and the extraction process, the powder may have
different properties for use in different kinds of products. For instance, Macrocystis
can give a medium-viscosity alginate, or a high viscosity with a careful extraction
procedure (lower temperature for the extraction). Sargassum usually gives a low
viscosity product. Laminaria digitata gives a soft to medium strength gel, while
Laminaria hyperborea and Durvillaea give strong gels. These are some of the reasons
why alginate producers like to have a variety of seaweed sources, to match the
alginate to the needs of particular applications.
Additional Resources
http://encarta.msn.com/encyclopedia_761573848/Algae.html
http://www.fao.org/DOCREP/006/Y4765E/y4765e08.htm
Kelp Forests. Judith Connor and Charles Baxter. Monterey Bay Aquarium.
http://www.seaweed.ie
Vocabulary
Seaweed – a form of marine algae.
Background
Many kinds of seaweed are edible and rich in vitamins and iodine. They are as
common in many Asian countries as green beans and carrots are in the United States. But
until more people here develop a taste for sea vegetables, it is alginates, carrageenan, and
beta-carotene -- seaweed derivatives that act as stabilizers, thickeners, and colorants -that end up on our dining room tables.
Seaweeds are not really weeds but large forms of marine algae that grow in the
coastal ocean waters of many countries. Marine algae include thousands of species
ranging from microscopic plants called phytoplankton to giant floating or anchored
plants, seaweeds.The three main groups of seaweed are brown, red, and green algae, each
providing important ingredients for the manufacture of food and other products.
Carrageenan is a generic term for compounds extracted from species of red algae.
Carrageen is used in stabilizing and gelling foods, cosmetics, pharmaceuticals, and
industrial products. From brown algae come alginates. They make water-based products
thicker, creamier, and more stable over extreme differences in temperature, ph, and time.
For example, alginates prevent ice crystals from forming in ice cream. Beta Carotene, a
natural pigment derived from green algae, is used as a yellow-orange food coloring and
may help prevent certain types of cancers.
These seaweed derivatives represent only a small part of the many living and
nonliving products we derive from ocean plants, animals, minerals, and seawater.
Together, they provide an important reason to protect the oceans.
©2009 Birch Aquarium at Scripps